CVE-2022-34835: i2c: fix stack buffer overflow vulnerability in i2c md command (8f8c04bf) · Commits · U-Boot / U-Boot

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Commit 8f8c04bf authored Jun 10, 2022 by Nicolas Iooss Committed by Tom Rini Jun 28, 2022

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i2c: fix stack buffer overflow vulnerability in i2c md command

When running "i2c md 0 0 80000100", the function do_i2c_md parses the length into an unsigned int variable named length. The value is then moved to a signed variable:

int nbytes = length;
#define DISP\_LINE\_LEN 16
int linebytes = (nbytes > DISP\_LINE\_LEN) ? DISP\_LINE\_LEN : nbytes;
ret = dm\_i2c\_read(dev, addr, linebuf, linebytes);

On systems where integers are 32 bits wide, 0x80000100 is a negative value to “nbytes > DISP_LINE_LEN” is false and linebytes gets assigned 0x80000100 instead of 16.

The consequence is that the function which reads from the i2c device (dm_i2c_read or i2c_read) is called with a 16-byte stack buffer to fill but with a size parameter which is too large. In some cases, this could trigger a crash. But with some i2c drivers, such as drivers/i2c/nx_i2c.c (used with “nexell,s5pxx18-i2c” bus), the size is actually truncated to a 16-bit integer. This is because function i2c_transfer expects an unsigned short le…

• Changes 1

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@@ -200,10 +200,10 @@ void i2c_init_board(void)

*

* Returns the address length.

*/

static uint get_alen(char *arg, int default_len)

static uint get_alen(char *arg, uint default_len)

{

int j;

int alen;

uint j;

uint alen;

alen = default_len;

for (j = 0; j < 8; j++) {

…

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@@ -247,7 +247,7 @@ static int do_i2c_read(struct cmd_tbl *cmdtp, int flag, int argc,

{

uint chip;

uint devaddr, length;

int alen;

uint alen;

u_char *memaddr;

int ret;

#if CONFIG_IS_ENABLED(DM_I2C)

…

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@@ -301,7 +301,7 @@ static int do_i2c_write(struct cmd_tbl *cmdtp, int flag, int argc,

{

uint chip;

uint devaddr, length;

int alen;

uint alen;

u_char *memaddr;

int ret;

#if CONFIG_IS_ENABLED(DM_I2C)

…

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@@ -469,8 +469,8 @@ static int do_i2c_md(struct cmd_tbl *cmdtp, int flag, int argc,

{

uint chip;

uint addr, length;

int alen;

int j, nbytes, linebytes;

uint alen;

uint j, nbytes, linebytes;

int ret;

#if CONFIG_IS_ENABLED(DM_I2C)

struct udevice *dev;

…

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@@ -589,9 +589,9 @@ static int do_i2c_mw(struct cmd_tbl *cmdtp, int flag, int argc,

{

uint chip;

ulong addr;

int alen;

uint alen;

uchar byte;

int count;

uint count;

int ret;

#if CONFIG_IS_ENABLED(DM_I2C)

struct udevice *dev;

…

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@@ -676,8 +676,8 @@ static int do_i2c_crc(struct cmd_tbl *cmdtp, int flag, int argc,

{

uint chip;

ulong addr;

int alen;

int count;

uint alen;

uint count;

uchar byte;

ulong crc;

ulong err;

…

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@@ -985,7 +985,7 @@ static int do_i2c_loop(struct cmd_tbl *cmdtp, int flag, int argc,

char *const argv[])

{

uint chip;

int alen;

uint alen;

uint addr;

uint length;

u_char bytes[16];

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